A plug-in hybrid vehicle in which merits of a hybrid vehicle and an electric vehicle are combined has been recently developed. Such plug-in hybrid vehicle requires a voltage higher than a general hybrid vehicle in order to drive a motor.
That is, the plug-in hybrid vehicle includes a high voltage battery supplying a voltage for driving the motor, a low voltage battery supplying a low voltage of 12V used for electronic components, a hybrid power control unit (HPCU), a motor MG1 for driving the vehicle, a generator MG2 for a start on/off, and an engine.
Among the above-mentioned components, the HPCU includes a cover protecting internal parts, an inductor boosting an input voltage, an inverter power module inverting a direct current (DC) voltage into an alternating current (AC) three-phase voltage, a capacitor for smoothing an input current, a high voltage connector, which is an interface supplying an AC output voltage to the motor, and a housing providing an internal part assembly interface and protecting the parts.
Since the inductor of the HPCU according to the related art is a main heating element of the HPCU and performance thereof is affected by a cooling, the inductor is indirectly cooled while being assembled to a heat radiating plate after grease is applied on the heat radiating plate.
However, the inductor increases cooling by increasing adhesion with the heat radiating plate using the grease, but as the grease is dissipated after a predetermined time, adhesion between the inductor and the heat radiating plate is weakened. As a result, the cooling of the inductor by the heat radiating plate may be significantly decreased and performance degradation of the inductor may occur.